The present invention relates to the field of suction cups, and in particular to axial suction cup installation and release devices and methods.
Suction cups are generally well-known and commonly used to mount and secure objects to smooth surfaces such as the surfaces of glass, plastic, Formica, glazed tile, metal, and other smooth surfaces. A typical suction cup includes a cup body and a stem. The cup body is generally arcuate or circular and defines a concavity. Typically, the stem is integrally formed on the body and used as the place of attachment for the object to be supported by the suction cup. At least the body of the suction cup is made of rubber, plastic or other material having sufficiently elastically resilient properties such that, when the body is pressed against a smooth surface, the volume of concavity is reduced, thereby forcing air to be expelled so that the body forms an air-tight seal against the smooth surface. Atmospheric pressure outside the body retains the suction cup body against the surface. When the air-tight seal is broken, air rushes into the concavity, releasing the vacuum and the suction attachment to the surface. Whereupon the elastically resilient material of the suction cup body returns to its relaxed condition. The resilient suction cup can be repeatedly reused.
Suction cups are difficult to properly position. Once a suction cup is attached to a surface, the suction forces (atmospheric and friction) resist repositioning of the cup. Attachment of the suction cup to an object can also be a problem. Preferably, the attachment should be releasable.
Furthermore, the vacuum within the suction cup resists the resilient force of the body so that the force of suction balances the resilient force of the body of the suction cup. The result is a limit on the degree of vacuum which can be achieved.
One way this limitation on the vacuum can be at least partially overcome is by xe2x80x9cpullingxe2x80x9d the center of the suction cup body away from the surface, thereby at least partially overcoming the restraining effect of the vacuum and generating an even greater vacuum. The periphery of the suction cup forms an air-tight seal with the surface. When the center of the suction cup body is pulled resiliently away from the surface, a partial vacuum is formed between the body and the surface so that the suction cup body xe2x80x9csticksxe2x80x9d to the surface. The greater the vacuum the better the cup sticks to the surface.
Several devices have been proposed to xe2x80x9cpullxe2x80x9d the center of the suction cup away from the surface in order to increase the suction. The most common arrangement, often found for example on the bases of pencil sharpeners and many kitchen appliances, involves a rod or crankshaft which extends mainly parallel to the surface to which the suction cup is to adhere. The center of the suction cup is attached to an eccentric section of the rod or crankshaft, and when a lever arm is turned, the center of the suction cup is pulled outward. U.S. Pat. No. 25 2,089,714, HOLDING DEVICE; issued Aug. 10, 1937, to Schuler; U.S. Pat. No. 3,765,638, SUCTION MOUNT, issued Oct. 16, 1973, to Harrison; and U.S. Pat. No. 4,934,641, CURVED SURFACE SUCTION MOUNTING APPARATUS, issued Jun. 19, 1990, to McElhaney, all of which are incorporated herein by reference, all describe such shaft-based arrangements.
One problem with arrangements using crankshafts and eccentric rods is the lever arms which extend out from whatever device they are mounted in. The lever arms is all too easy to hit or snagged, and the suction is thereby accidentally released. Another drawback of lever arms is that the support and bearing structure for them is difficult to integrate into the structure of the device which is utilizing the suction cups. This complication increases costs and the likelihood of failure.
A further cause of increased costs associated with such suction cup assemblies according to the prior art is that they usually require suction cups that must be specially designed to accommodate the lever arms, crankshafts, and the like.
More recently, U.S. Pat. No. 5,087,005, TWIST-CAM SUCTION CUP ASSEMBLY, issued Feb. 11, 1992, to Holoff, et al. and U.S. Pat. No. 5,381,990, RELEASABLE SUCTION CUP ASSEMBLY, issued Jan. 17, 1995, to Belokin, et al., both incorporated herein by reference, proposed devices for xe2x80x9cpullingxe2x80x9d the center of the suction cup axially.
Holoff, et al., for example, discloses a suction cup assembly having a suction cup, a cam member, a cone member and a mating core member secured to the suction cup. The cone member has an outer periphery generally co-extensive with an outer portion of the suction cup, and a generally cylindrical inner opening closely enclosing a cylindrical outer surface of the core member. The cam member has generally cylindrical camming surfaces, and is mounted onto and closely engages either the core member or a camming flange on the cone member, depending on the embodiment. The cam member axially shifts the core member outward relative to the cone member by pulling the center of the suction cup away from a surface to which the suction cup may be adhered.
Belokin, et al. discloses a releasable suction cup formed by a cup body which has a duct passing therethrough and a valve element for opening the duct, whereby the vacuum holding the suction cup can be released for repositioning the suction cup. The valve extends through the duct and is threaded on one end to receive a threaded fastener which is used to move the valve element into a sealing position and to secure the suction cup to an object.
The axial suction cup devices of Holoff, et al. and Belokin, et al. and others however are overly complex to manufacture, assemble and operate, as well as suffering other limitations.
A compact axially-driven suction cup installation mechanism including a substantially rigid rotational drive mechanism having a tubular frame forming a substantially planar drive surface at one end thereof, a pair of diametrically opposed spiral installation drive members projecting inwardly from an internal wall surface of the tubular frame and being supported at first and second ends by a pair of diametrically opposed longitudinal stanchions projecting inwardly from the internal wall surface of the tubular frame, internal edge surfaces of the spiral installation drive members and longitudinal stanchions forming a longitudinal aperture axially aligned with the internal wall surface of the tubular frame, and means for manually rotating the tubular frame; a housing having a substantially planar external drive surface formed with an aperture therethrough and being structured to cooperate with the substantially planar drive surface of the rotational drive mechanism; and a columnar drive shaft structured to travel through the longitudinal aperture of the rotational drive mechanism, a first end of the columnar drive shaft including means for connecting to a suction cup and a second end of the columnar drive shaft including means for interacting with one or both of the pair of spiral installation drive members for moving the columnar drive shaft through the longitudinal aperture of the rotational drive mechanism in an outwardly direction relative to the planar drive surface thereof
According to one aspect of the invention, the means of the columnar drive shaft for interacting with the spiral installation drive members of the rotational drive mechanism is structured as a rigid installation drive pin installed crosswise to the columnar drive shaft.
According to another aspect of the invention, the means for connecting to a suction cup includes a structure adapted for being molded into the suction cup.
According to another aspect of the invention, a suction cup having a central attachment portion is included, the central attachment portion being coupled to the suction cup connecting means of the columnar drive shaft.
According to another aspect of the invention, the housing includes a concavity positioned on a surface opposite from the external drive surface thereof and is structured to admit a central flexible portion of a suction cup, the aperture communicating between the external drive surface and the concavity.
According to another aspect of the invention, the rotational drive mechanism further includes a pair of diametrically opposed spiral release drive members each projecting inwardly from an internal wall surface of the tubular frame on an opposite surface of the spiral installation drive members and being supported at first and second ends by the pair of diametrically opposed longitudinal stanchions projecting inwardly from the internal wall surface of the tubular frame; and the second end of the columnar drive shaft further includes means for interacting with one or both of the pair of spiral release drive members for moving the columnar drive shaft through the longitudinal aperture of the rotational drive mechanism in a second direction relative to the planar drive surface thereof opposite from the first direction. The means of the columnar drive shaft for interacting with the spiral release drive members of the rotational drive mechanism is, for example, a rigid release drive pin installed crosswise to the columnar drive shaft at a position between the installation drive pin and the means for connecting to a suction cup.
According to another aspect of the invention, the housing includes a utilization mounting surface structured as a pattern of mounting holes spaced away from the housing planar drive surface a distance sufficient to admit the rotational drive mechanism therebetween.